Fuel injection systems are conventionally composed of an electronic part and a hydraulic part. In the hydraulic part, the fuel is compressed to a predefined pressure, so that during the injection process into a combustion chamber, such as for example a cylinder, the requested quantity of fuel or a desired quantity of fuel can be introduced with optimized atomization. In order for the method to proceed correctly, it is necessary to have knowledge of the fuel pressure which is typically measured by means of pressure sensors. Errors or deviations of the measured fuel pressure from the actual fuel pressure can give rise to deviating injection quantities, to non-optimum atomization of the fuel and therefore to worsening of emissions or worsening of the performance of the internal combustion engine. It is therefore basically necessary to determine the fuel pressure with sufficient accuracy, which is typically done by means of pressure sensors. In addition it is necessary to check the plausibility of the measured values supplied by the pressure sensor, since during operation it can lead to drifting or even to failure of the sensor.
Measurement of the fuel pressure is conventionally carried out using a pressure sensor. The checking of electrical parameters of the fuel pressure sensor can serve here to check the functioning of the sensor or to check the plausibility.
However, it has been observed that a pressure measurement by means of a pressure sensor cannot be carried out in all situations with sufficient accuracy and reliability. Plausibility checking of the measured values of a pressure sensor by monitoring electrical parameters is also not reliable in all situations and circumstances. In addition, under certain circumstances, a pressure measurement by means of a pressure sensor may not have sufficient accuracy.